1. Field of the Invention
The present invention relates to a chest expander.
2. Description of the Related Art
A chest expander is one of sporting goods used for exercising arms and shoulders. The chest expander is operated by gripping both grip parts formed at lower ends of a pair of arms of the chest expander, using both hands of a user. The user pushes the both arms to approach the arms toward each other, and releases the both arms to space them apart from each other, thereby exercising his/her arms, chest and shoulders. The user can repeat the above movement to increase his/her arm and shoulder muscle power.
A conventional chest expander uses a tension coil spring to use the muscle power when the user pushes the both arms to approach them together. That is, when the arms come toward each other, the coil spring is extended to apply a power in an opposite direction of the movement of the user, thereby exercising his/her muscle power.
However, when the chest expander uses the tension coil spring, a stress is concentrated on a hook part formed at a tip of the tension coil spring for connecting the arm to the tension coil spring such that the hook part can be readily broken. As a result, a reduction in durability and lifespan of the chest expander may be a major complaint of users.
In addition, since the arms of the conventional chest expander are supported by separate tension coil springs, the number of components is increased and a resilient force of the coil spring should be precisely adjusted to uniformly distribute power applied to the both arms.